Botryodiplodia canker of maple

Pathogen and type of disease
Botryodiplodia acerina is the fungal pathogen responsible for Botryodiplodia canker of maple. This disease belongs to the category of necrotrophic bark infections. The fungus targets the cortical tissues of the host plant, resulting in localized or systemic necrosis that can severely compromise the structural integrity and health of the tree.

Susceptible crops
The disease primarily affects maple trees (Acer species). It is frequently observed in urban landscapes, nurseries, and managed forests. Trees that are already stressed due to environmental factors such as drought, soil compaction, mechanical wounds, or insect infestations are significantly more susceptible to infection by this pathogen.

Symptoms and signs of infection
The diagnostic symptoms include the development of depressed, discolored lesions on the bark of trunks and branches. As the pathogen colonizes the tissue, the bark cracks and creates openings through which the fruiting bodies (pycnidia) of the fungus emerge as small black pustules. Foliage on infected branches often shows signs of chlorosis, wilting, and premature abscission due to the disruption of water and nutrient transport.

Development conditions and impact
The development of the fungus is favored by high humidity, moderate temperatures, and weakened host immunity. Spores are dispersed through rain splash, wind, and potentially by insects moving from tree to tree. The impact of the disease is considerable, as it leads to limb dieback, reduced aesthetic value, and eventually the death of the entire tree if the girdling effect reaches the main trunk.

Protective and preventive measures
Effective management requires a combination of horticultural hygiene and chemical intervention:

• Regular sanitation pruning to remove infected wood, ensuring tools are disinfected between cuts.
• Application of wound dressings or protective paints on large pruning cuts to prevent colonization.
• Improving overall tree vitality through appropriate irrigation, mulching, and nutrient management.
• Removal and destruction of debris from around the tree base to minimize the inoculum source.
• Applying fungicides during the dormancy or early growing season to protect healthy trees in affected areas.